The invention relates to a process and equipment for elimination of various production wastes for environment protection, and in particular to a process and cyclone reactor for fire decontamination of industrial waste water containing organic and refractory mineral impurities.
Mineral impurities are divided herein into fusible and refractory impurities depending on the temperature of elimination of organic impurities. If the mineral impurities are melted below this temperature, they are attributed to fusible impurities, and if their melting point lies above this temperature, they are referred to as refractory ones.
The process and reactor according to the invention may be successfully employed for fire decontamination of local industrial waste water of chemical production processes in various industries.
For a large group of industrial waste water, the application of widely used methods of purification (chemical and biochemical methods) is frequently useless. This is especially true for purification of production waste water containing a large variety of organic and mineral impurities with high concentration thereof. Many impurities of industrial waste water are toxical for microorganisms so that they cannot be decontaminated by the biochemical method. The fire decontamination with the employment of furnaces of various designs is now widely used for practical solution of the problems involving such waste water.
Known in the art is a process for fire decontamination of industrial waste water containing organic and refractory mineral impurities comprising feeding waste water in a sprayed state into a high-temperature fuel spray of a furnace in which liquid or gaseous fuel is burnt. The gas temperature in the furnace is maintained at a level sufficient for melting the particles of refractory mineral impurities formed after the evaporation of drops of the waste water and burning out of organic impurities.
Refractory mineral impurities are discharged from the furnace mainly in the form of a melt, and partially -- with fume gases, in the form of fine dust particles.
The main disadvantage of the above -described method consists in an elevated fuel consumption for conducting the decontamination process due to the need in melting refractory mineral impurities. Thus, the temperature level in the furnace is considerably above the gas temperature required for complete burning out of organic impurities. It is also known to decontaminate waste water containing organic and refractory mineral impurities comprising feeding waste water in a sprayed state into a furnace, wherein the temperature is maintained at a level sufficient for burning out organic impurities but considerably lower than the melting temperature of refractory mineral impurities. In this case, solid particles of refractory mineral impurities formed after the evaporation of drops of the waste water are entrained from the furnace with fume gases so that they should be caught in wet or dry scrubbers installed after the furnace.
This method is advantageous in that it has a low specific fuel consumption for conducting the decontamination process determined by a minimum temperature of fume gases necessary to completely burn out organic impurities.
However, this conventional method is deficient in that it requires cumbersome and complicated equipment for purification of gases from finely divided dust particles, because refractory mineral impurities are substantially completely entrained with fume gases from the furnace.
Known methods can be carried out in various furnaces, such as shaft furnaces and cyclone reactors.
Known in the art is a shaft furnace for fire decontamination of waste water containing organic and refractory mineral impurities comprising a vertical shaft having burner apparatus located in the bottom portion thereof for combined feeding of fuel and air for burnng the organic fraction of the fuel and organic impurities of waste water. Located above the burner apparatus in the transverse plane of the shaft there are injection nozzles for feeding waste water. In the bottom portion of the shaft there is provided a tap for discharging a melt of mineral impurities, and an opening for discharging fume gases is located in the bottom portion. Equipment for purification of fume gases from particles of mineral impurities is installed after the opening for discharging fume gases.
The operation of such furnace by any of the above-described methods is characterized by a low specific capacity in terms of the weight of waste water being decontaminated per one cubic meter of the furnace volume per hour, low ratio of catching of mineral impurities, high heat losses in the combustion chamber. This results in greater capital investments and high operating cost.
The most efficient and flexible apparatus for conducting such processes is a cyclone reactor.
A conventional cyclone reactor for fire decontamination of waste water comprises a vertical cylindrical chamber having dimensions depending on the capacity of the reactor and physical and chemical composition of the waste water being decontaminated. The top portion of the chamber is made of refractory and isolating brick to ensure a reliable stability of the fuel combustion and is provided with a tapered, flat or dome-shaped cover. Burner apparatus are located in the top portion of the chamber and are arranged tangentially to the walls thereof and equally spaced apart along the generatrix for combined feeding of fuel and air into the chamber for burning the organic fraction of the fuel and organic impurities of the waste water. The portion of the chamber disposed below the top portion thereof is cooled with water and is provided with a chilled lining. Injection nozzles for feeding and spraying waste water in the chamber are arranged on the periphery of the chamber below the burner apparatus and tangentially to the walls of the chamber. In the bottom portion of the chamber there is provided a base with an opening communicating this chamber with a gas duct for discharging combustion products and a melt of mineral impurities.
A tap for discharging the melt of mineral impurities is located in the bottom portion of the gas duct.
In the course of the above-described processes of fire decontamination of waste water in such cyclone reactor, high specific loads of decontaminated liquor per volume of the reactor are achieved.
However, this known cyclone reactor is deficient in that, with the radial arrangement of the injection nozzles on the periphery of the chamber thereof, refractory mineral impurities should be melted, because otherwise they will be entrained with fume gases. At the same time, in order to melt refractory mineral impurities, the temperature of the fume gases should be maintained at a level above the melting temperature of these mineral impurities. Thus, the temperature level in the reactor will considerably exceed the temperature of the fume gases required for complete burning out of organic impurities and melting fusible mineral impurities, whereby the fuel consumption is increased.
The conduct of the process of fire decontamination of waste water at a temperature of fume gases discharged from the reactor sufficient for complete burning out of organic impurities results in a considerable amount of dust of refractory mineral impurities leaving the cyclone reactor with the fume gases. It should be noted, that complicated and expensive equipment is required for catching refractory mineral impurities by purifying the fume gases containing finely divided impurities.